I was browsing through Christianbook's sale list and found several Rose Publishing pamphlets for $.79. There are others, but these are the ones that I wanted and didn't already have.
The Life of the Apostle Paul
Life of Moses
50 Proofs For the Bible, New Testament
50 Proofs For the Bible, Old Testament
All four of these pamphlets include a link and password that will get you a PDF version emailed to you.
Rose Publishing books at Christianbook only allow a single download. I've found, though, that if you bookmark the download link in your browser before downloading, you can re-download the book from the bookmark if you're logged into your Christianbook account.
Baker Publishing and B&H also have quite a few books on sale. I already have the ones that I want, but there's a mix of apologetics, theology and fiction that might be worth looking through if you're into any of those.
E-books on sale, sorted by price.